cf_client.py

import threading

try:
    from curl_cffi import requests as cffi_requests
    _use_cffi = True
except ImportError:
    _use_cffi = False

try:
    import cloudscraper
except ImportError:
    cloudscraper = None

_thread_local = threading.local()


def get_session():
    """Returns a session that bypasses Cloudflare. curl_cffi preferred, cloudscraper fallback."""
    session = getattr(_thread_local, 'session', None)
    if session is not None:
        return session

    if _use_cffi:
        session = cffi_requests.Session(impersonate='chrome')
    elif cloudscraper:
        session = cloudscraper.create_scraper(
            browser={'browser': 'firefox', 'platform': 'windows'}, delay=10
        )
    else:
        raise ImportError("Install curl_cffi or cloudscraper for Cloudflare bypass")

    _thread_local.session = session
    return session


def fetch(url, headers=None, timeout=20, use_proxy=False, proxy_url=None):
    """Fetch a URL bypassing Cloudflare. Returns response object."""
    session = get_session()
    kwargs = {'headers': headers or {}, 'timeout': timeout}
    if use_proxy and proxy_url:
        kwargs['proxies'] = {'http': proxy_url, 'https': proxy_url}

    if _use_cffi:
        kwargs['headers'] = {k: v for k, v in kwargs['headers'].items()
                            if k.lower() != 'user-agent'}

    resp = session.get(url, **kwargs)
    return resp


def is_cloudflare_blocked(resp):
    """Check if a response is a Cloudflare interstitial."""
    if resp.status_code in (403, 429, 503):
        return True
    body = resp.text[:3000].lower()
    return ('just a moment' in body or 'cf_chl_' in body
            or 'cf-browser-verification' in body or 'attention required' in body)